Photo film cassette

ABSTRACT

A photo film cassette has a spool core about which photo film is wound in a form of a roll. A cassette shell contains the spool core in a rotatable manner. Two flanges have a disk shape, and are secured to respective ends of the spool core, for regulating lateral edges of the roll of the photo film. A circumferential lip is disposed on each flange, is extended toward the opposite one of the flanges, wraps one of the lateral edges of an outermost turn of the photo film of the roll, and prevents the photo film from being loosened. A rim portion is disposed on an circular edge of the circumferential lip confronted with the opposite one of the flanges, to project with a bend away from the spool core. A contact face is disposed on the rim portion, and contacts the one of the lateral edges of the photo film when the photo film is unwound from the spool core or wound back about the spool core. The contact face has a contact range of 0.15-0.8 mm in contacting the one of the lateral edges of the photo film.

This is a divisional of U.S. application Ser. No. 09/133,817 filed Aug.13, 1998 U.S. Pat. Ser. No. 6,065,702, the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photo film cassette. Moreparticularly, the present invention relates to a photo film cassette ofa type in which rotation of a spool advances a leader of photo film tothe outside, and which includes improved flanges of the spool.

2. Description Related to the Prior Art

There are various documents U.S. Pat. No. 5,296,887, JP-A 2-18545(corresponding to U.S. Pat. No. 4,848,693) and JP-A 4-320258(corresponding to U.S. Ser. No. 655,944) which suggest a photo filmcassette in which a cassette shell consists of molded parts of resin,and rotation of a spool core causes a leader of photo film to advance tothe outside of the cassette shell. U.S. Pat. No. 5,083,155(corresponding to JP-A 3-179341) suggests a container for containingdeveloped photo film, the container including the cassette shell of thesame structure for the purpose of facilitating handling and preservationof the developed photo film.

The photo film cassette includes a pair of flanges, which are disposedon respective axial ends of the spool core. There are circumferentiallips formed on the respective periphery of the spool flanges to transmitrotation of the spool core reliably to the roll of the photo film. Thecircumferential lips partially wrap lateral edges of the outermost turnof the photo film to prevent the photo film from being loosened. In thecourse of advance and rewinding of the photo film, rigidity of the photofilm causes the spool flanges to flex. Therefore the circumferentiallips squeeze the lateral edges of the photo film between them.

In the course of advance of the photo film, the spool flanges must bespread by the photo film in the vicinity of the photo film passageway,in order to release the photo film from being partially wrapped by thecircumferential lips. The spool flanges rotate always with deformation,and thus are originally formed with a small thickness. On the otherhand, the spool flanges require sufficient rigidity, resistance toabrasion and other conditioned characteristics. Typically thecircumferential lips must have considerable rigidity and resistance toabrasion for the reason of frictional contact with the lateral edges ofthe photo film in the course of the advance and rewinding of the photofilm.

To provide the spool flanges with sufficient rigidity and resistance toabrasion, appropriate material for forming the spool flanges should beselected. Also an appropriate molding method for the spool flanges mustbe used. For example, documents such as U.S. Pat. No. 5,211,348(corresponding to JP-A 4-251841), JP-A 6-148808 and U.S. Ser.No. 531,966(corresponding to JP-A 8-146562) suggest a flange forming method. Apolyethylene resin sheet is formed by extrusion with a thickness of 0.3mm, and then heated and softened. Flange-shaped portions are formed byvacuum forming or pressure sure forming of the resin sheet, and thenpunched to obtain the spool flanges.

No matter whether good the material is to be used for the spool flangesin view of the rigidity and resistance to abrasion, the edge of thecircumferential lips of the spool flanges of the prior art, having arounded shape, still contacts the lateral edges of the photo filmfrictionally at one point. There remains possibility in rubbing thecircumferential lips to create scraped powder or dust.

When the scraped powder or dust is created inside a camera, it is likelyto be stuck on the photo film in exposure regions to lower photographicquality. The photo film according to the IX 240 type (Advanced PhotoSystem, trade mark) is also provided with magnetic recording layer. Thescraped powder or dust in the camera is likely to deposit on a magnetichead to cause failure in properly writing data to, or reading data from,the magnetic recording layer.

SUMMARY OF THE INVENTION

In view of the foregoing problems, an object of the present invention isto provide a photo film cassette of a type in which rotation of a spooladvances a leader of photo film to the outside, and in which thecircumferential lips of the spool flanges are prevented from beingfrictionally rubbed by the photo film.

Another object of the present invention is to provide a photo filmcassette having flanges of which supply and conveyance are preventedfrom being influenced by occurrence of electrostatic charge betweenflanges, and between a flange and a part feeder which conveys theflange.

Still another object of the present invention is to provide a photo filmcassette of which flanges can be molded consecutively one after anotherat remarkably higher speed.

In order to achieve the above and other objects and advantages of thisinvention, a photo film cassette includes a spool core about which photofilm is wound in a form of a roll, a cassette shell for containing thespool core in a rotatable manner, first and second flanges, having adisk shape, and secured to respective ends of the spool core, forregulating lateral edges of the roll of the photo film, acircumferential lip, disposed at least on the first flange, extendedtoward the second flange, for wrapping one of the lateral edges of anoutermost turn of the photo film of the roll, to prevent the photo filmfrom being loosened. A rim portion is disposed on an circular edge ofthe circumferential lip confronted with the second flange, to projectwith a bend away from the spool core. A contact face is disposed on therim portion, for contacting the one of the lateral edges of the photofilm when the photo film is unwound from the spool core or wound backabout the spool core, the contact face having a contact range of0.15-0.8 mm in contacting the one of the lateral edges of the photofilm.

In a preferred embodiment, the contact face is inclined away from thespool core in a projecting direction of the rim portion, for reducingresistance of the circumferential lip against the photo film when thephoto film is unwound from the spool core or wound back about the spoolcore.

The contact face is an at least partially conical surface.

The contact range is obtained by drawing the photo film out of thecassette shell for inspection, embedding an inside of the cassette shellwith test resin, hardening the test resin, further drawing the photofilm out of the cassette shell, polishing the test resin, and when asurface of the photo film appears by polishing the test resin, measuringa range where the photo film appears.

Furthermore, a photo film passageway is formed in the cassette shell,and adapted to advance and rewinding of the photo film therethrough. Aseparator claw is disposed in the cassette shell, for separating theoutermost turn of the photo film from the roll when the spool core isrotated in an unwinding direction while an entirety of the photo film iscontained in the cassette shell, to direct the outermost turn to thephoto film passageway.

Consequently the circumferential lips of the spool flanges are preventedfrom being frictionally rubbed by the photo film.

In another preferred embodiment, the first and/or second flange includesone bottom face being substantially flat. At least one supportprojection, disposed to project from the bottom face, directed downwardswhen conveyed and supplied, for supporting the bottom face, to reduce anarea where the bottom face is contacted externally.

The bottom face is positioned opposite to the roll of the photo film.

The first and/or second flange is formed from resin, has a weight of 0.5gram or less, and has an average thickness of 0.4 mm or less.

The at least one support projection is semi-spherical or conical.

Consequently supply and conveyance of flanges are prevented from beinginfluenced by occurrence of electrostatic charge between flanges, as thecontacting area is reduced.

In a further preferred embodiment, the circumferential lip has an innersurface confronted with the roll of the photo film. At least one ridgeis disposed to project from the inner surface.

The circumferential lip further has an outer surface positioned oppositeto the roll of the photo film. The first flange is molded from resin.During molding of the first flange, the at least one ridge sets arelease of the inner surface later than a release of the outer surface.

The at least one ridge is arc-shaped as viewed in section, and extendsin a circular direction of the inner surface.

A projecting height of the at least one ridge is 0.005-0.10 mm.

Consequently efficiency in the release of the molded flange from themold is raised. The flanges can be molded consecutively one afteranother at remarkably higher speed.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will becomemore apparent from the following detailed description when read inconnection with the accompanying drawings, in which:

FIG. 1 is an exploded perspective illustrating photo film cassette;

FIG. 2 is a side elevation illustrating the photo film cassette;

FIG. 3 is a side elevation opposite to FIG. 2, illustrating the photofilm cassette;

FIG. 4 is a horizontal section illustrating a spool;

FIG. 5 is a side elevation illustrating a first flange;

FIG. 6 is a side elevation illustrating a second flange;

FIG. 7A is an explanatory view in cross section, illustrating each ofthe flanges;

FIG. 7B is an explanatory view in enlargement, illustrating the flangewith a circumferential lip;

FIG. 7C is an explanatory view in enlargement, illustrating thecircumferential lip with a rim portion;

FIG. 8 is a graph illustrating a relationship between the number oftimes of repeated advance of the photo film and an angle of a contactface;

FIG. 9 is a graph illustrating a degree of scrape of the circumferentiallip and the angle of the contact face;

FIG. 10A is an explanatory view illustrating another preferredcircumferential lip of which an edge is rounded;

Figs. 10B and 10C are explanatory views illustrating still otherpreferred circumferential lips;

FIG. 11A is a perspective illustrating another preferred flange havingsupport projections;

Fig. 11B is a plan illustrating the flange of FIG. 11A;

FIG. 12A is a perspective illustrating a flange opposite to that of FIG.11A;

FIG. 12B is a plan illustrating the flange of FIG. 12A;

FIG. 13A is an explanatory view in cross section, illustrating theflange of FIGS. 12A an 12B;

FIG. 13B is an explanatory view in enlargement, illustrating the flangewith a circumferential lip;

FIG. 13C is an explanatory view in enlargement, illustrating one of thesupport projections;

FIG. 14A is a perspective illustrating still another preferred flangehaving an inner ridge;

FIG. 14B is a perspective illustrating a flange opposite to that of FIG.14B;

FIG. 15A is an explanatory view in cross section, illustrating theflange of FIG. 14A;

FIG. 15B is an explanatory view in enlargement, illustrating the flangewith a circumferential lip;

FIG. 15C is an explanatory view in enlargement, illustrating thecircumferential lip with the inner ridge; and

FIG. 16A-16C are explanatory views illustrating the flange of FIG. 14Bincluding the circumferential lip and the inner ridge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENTINVENTION

In FIG. 1, a photo film cassette 10 includes a cassette shell 11, whichcontains a spool 13 in a rotatable manner with photo film 12 woundthereabout in a roll form. When the spool 13 is rotated in a directionto unwind the photo film 12, a leader of the photo film 12 is exited tothe outside of the cassette shell 11.

The cassette shell 11 is constituted by shell halves 14 and 15 each ofwhich is a molded part of resin. The shell half 15 has retainer hooks16, which are retained on the shell half 14, to secure the shell half 15to the shell half 14 in a fixed manner. A label or sticker 17 isattached to the outside of the cassette shell 11.

The inside of the cassette shell 11 are divided into three, including aninformation chamber 18, a photo film chamber 19 and an indicator chamber20. There is a photo film passageway 21 formed along a portion of thejuncture between the shell halves 14 and 15. The photo film passageway21 has a cassette shutter 22 and a separator claw 23. The cassetteshutter 22 is openable, and when closed, prevents ambient light fromentry into the cassette shell 11. The separator claw 23 is disposed inthe cassette shell 11, and separates the leader of the spool 13 from theroll. Respective ends of the cassette shutter 22 has keys 24 and 25.When a camera is loaded with the photo film cassette 10, one of the keys24 and 25 is connected with an opener drive shaft. When the drive shaftis rotated, the cassette shutter 22 is set at one of open and closedpositions for the photo film passageway 21.

The spool 13 includes a spool core 26, a pair of flanges 27 and 28 and abarrel member 29, each of which is a molded part of resin. The spoolcore 26 is a one piece including a data plate 30, receiver portions 31and 32, a slit 33, a barrel receiver 34 and keys 35 and 36. The receiverportions 31 and 32 is used for receiving the respective flanges. Theslit 33 is formed for retention of a trailer of the photo film. When acamera is loaded with the photo film cassette 10, one of the keys 35 and36 is engaged with a drive shaft of the camera, which causes the spoolcore 26 to rotate.

The slit 33 has push ridges 33 a and 33 b and retainer claws 33 c and 33d. The push ridges 33 a and 33 b have resiliency. The retainer claws 33c and 33 d are engaged with respective retainer holes 12 b and 12 cformed in a trailer 12 a of the photo film 12. A slot 12 d is formedbetween the retainer holes 12 b and 12 c, and receives both the pushridges 33 a and 33 b. The push ridges 33 a and 33 b retain the trailer12 a of the photo film 12 and keep the retainer claws 33 c and 33 d frommoving away from the retainer holes 12 b and 12 c. After the trailer 12a is retained on the spool core 26, the photo film 12 is wound about thespool core 26.

The barrel member 29 is one piece including a disk 38, a gear 39 and anindicator plate 40. The disk 38 has ratchet claws 37. All those portionsof the barrel member 29 is rotatable together with the spool core 26.

When the spool 13 with the roll of the photo film 12 is inserted in thecassette shell 11, the flanges 27 and 28 are contained in the photo filmchamber 19 with the photo film 12. The data plate 30 is contained in theinformation chamber 18. The indicator plate 40 and the gear 39 arecontained in the indicator chamber 20.

A label or sticker 41 is attached to the data plate 30, and has a barcode 41 a printed thereon. The bar code 41 a represents information ofthe photo film sensitivity, the number of available frames, the photofilm type, and the like. The bar code 41 a, when the photo film cassetteis loaded in a camera or a photographic printer, is read by a bar codereader or sensor in it. The shell half 14, as illustrated in FIG. 2, hasa reader opening 42, through which the bar code 41 a is accessed andread while the spool 13 is rotated in the unwinding direction. Note thatthe bar code 41 a may be directly printed on the data plate 30 by padprinting or hot stamping, that is the foil stamping, without the use ofthe sticker 41. Also a bar code label with the bar code 41 a may beprovided by thermal transfer in the course of molding the spool core 26instead of the pad printing or hot stamping.

The indicator plate 40 is used for indicating one of used statuses ofthe photo film 12 inside the cassette shell 11, the used statusesincluding an unexposed status, an exposed undeveloped status, and adeveloped status. The indicator plate 40, as depicted in FIG. 3, ispositioned on the rear of one of indicator windows 43, 44, 45 and 46formed in an outer wall of the indicator chamber 20. Each of theindicator windows 43, 44, 45 and 46 is associated with one of the usedstatuses, and pointed by the indicator plate 40 to signal theinformation in a visually recognizable manner.

A spool lock 47 is contained in the indicator chamber 20 for meshingwith the gear 39. The spool lock 47 allows the spool 13 to rotate whenthe cassette shutter 22 is in the open position, and blocks rotation ofthe spool 13 when the cassette shutter 22 is in the closed position. InFIG. 3, the spool lock 47 includes a main arm 47 a and end arms 47 b and47 c, which are extended from the main arm 47 a in a resilient manner.An engaging claw 47 d is disposed at the center of the main arm 47 a.

When the cassette shutter 22 is in the closed position, the end arm 47 bcontacts a key 48. Thus the engaging claw 47 d is pressed against thegear 39, and kept in mesh with the gear 39 to stop the spool 13 fromrotating. The photo film cassette 10 being unused has the cassetteshutter 22 in the closed position. The spool 13 does not rotate.

The end arm 47 c contacts an engaging projection 49 disposed inside theindicator chamber 20, and biases the main arm 47 a in a direction ofdisengaging the engaging claw 47 d from the gear 39. When the cassetteshutter 22 is in the open position, the key 48 is released from pushingthe end arm 47 b. Then the end arm 47 c disengages the engaging claw 47d from the gear 39, so that the spool 13 becomes free. The opener driveshaft of the camera causes the cassette shutter 22 to rotate to the openposition. The spool 13 is allowed to rotate. Then the photo film isadvanced or rewound.

In FIG. 4, the flanges 27 and 28 are secured to the receiver portions 31and 32 between the data plate 30 and the barrel member 29 with a gapenough for a width of the photo film 12 to position it between them. Inthe process of assembly of parts of the spool, the flanges 27 and 28 aremoved in the same direction in the insertion of the spool core 26, inconsideration of ease in the assembly. The receiver portions 31 and 32of the spool core 26 have different diameters. Also the flange 27 has alarge-diameter hole 27 a, and the flange 28 has a small-diameter hole 28a. The flange 27 of FIG. 6 is moved past the receiver portion 32 atfirst, and then reaches the receiver portion 31 to engage thelarge-diameter hole 27 a therewith. The flange 28 is secured to engagethe small-diameter hole 28 a with the receiver portion 32. On either ofthe sides, the flanges 27 and 28 are rotatable on the receiver portions31 and 32.

In FIG. 5, the flange 28 has four holes 28 b, which are arranged in acircumferential manner at a constant angular pitch. When the spool core26 is rotated in the unwinding direction, the ratchet claws 37 of thebarrel member 29 enter corresponding ones of the four holes 28 b, andbecome engaged therewith. The ratchet claws 37, when engaged, transmitrotation of the spool core 26 to the flange 28 via the holes 28 b. Whenin contrast the spool core 26 is rotated in the winding direction, theratchet claws 37 are disengaged from the holes 28 b, and do not transmitrotation of the spool core 26 to the flange 28.

In FIG. 4, the flanges 27 and 28 have circumferential lips 27 b and 28c. When the spool core 26 rotates in the unwinding direction, thecircumferential lips 27 b and 28 c wrap ends of the roll of the photofilm 12, to transmit rotation of the spool core 26 to the outer turns ofthe roll, and also to keep the photo film 12 from being loosened. Againin the course of rewinding the photo film 12 about the spool core 26,the circumferential lips 27 b and 28 c prevent the photo film 12 frombeing loosened.

In FIGS. 7A-7C, ring-shaped edges of the circumferential lips 27 b and28 c of the flanges 27 and 28 are provided with rim portions 8 a and 8b, which are directed outwards with respect to the shape of the flanges.Let θ be an inclination angle of the rim portions 8 a and 8 b withreference to a straight line L1 lying on two opposite points of each ofthe circumferential lips 27 b and 28 c and as viewed in the crosssection of the flanges 27 and 28 taken in the direction of therotational axis of the flanges 27 and 28. The inclination angle θ ispreferably in a range of 5-50°, and desirably in a range of 10-35°.There are inclined contact faces 9 a and 9 b respectively on the rimportions 8 a and 8 b of the circumferential lips 27 b and 28 c. Theinclined contact faces 9 a and 9 b are a curved surface of a portion ofa cone, which is triangular as viewed in cross section with a straightline. Let L be a length of the inclined contact faces 9 a and 9 b. Thelength L is preferably in a range of 0.15-0.8 mm, and desirably in arange of 0.2-0.5 mm.

The circumferential lips 27 b and 28 c are bent with an inclination atthe rim portions 8 a and 8 b in the range of 5-50° in a direction tospread edges of the circumferential lips 27 b and 28 c outwards. Theinclined contact faces 9 a and 9 b are formed with the circumferentiallips 27 b and 28 c in the range of 0.15-0.8 mm, to determine aconsiderably large area of the contact of lateral edges of the photofilm 12 with the circumferential lips 27 b and 28 c. Accordingly thephoto film 12 can contact the circumferential lips 27 b and 28 c in areliably great range in the course of both advance and rewinding. Forceof the push of the photo film 12 to the circumferential lips 27 b and 28c per unit area is reduced. It is possible to lower an amount of scrapeor abrasion of the circumferential lips 27 b and 28 c, and reduce anamount of plastic powder from scrape or abrasion.

When the spool core 26 is rotated in the unwinding direction, the leaderof the photo film 12 comes to contact the separator claw 23, and isseparated by it from the roll of the photo film 12, and is directed tothe photo film passageway 21. The photo film 12 is advanced to theoutside of the cassette shell 11 while spreading the circumferentiallips 27 b and 28 c of the flanges 27 and 28. There are flange regulatorridges 50, disposed inside the photo film chamber 19, for preventing theflanges 27 and 28 from being spread outwards in regions different fromthe photo film passageway 21. See FIG. 1.

It is to be noted that the length L of the partial conical surface ofthe inclined contact faces 9 a and 9 b, which is straight as viewed incross section, is obtained in approximation by experimental measurementin which epoxy resin is used.

The length L is measured by the following process. At first the photofilm is kept drawn from the photo film cassette. The whole of the photofilm cassette is embedded in epoxy resin without leaving bubble in theresin. The epoxy resin is hardened. After this, a surface parallel to asurface of the photo film is polished or rubbed gradually. The polishingor rubbing is stopped when the photo film surface appears. The contactlength between the lip end and the photo film is measured.

Of course the length L of the partial conical surface of the inclinedcontact faces 9 a and 9 b may be measured directly, or by any suitableprocesses other than the above embedding process with the epoxy resin.

It is likely that a range of the inclined contact faces 9 a and 9 bobtained experimentally after the embedment and polish of the epoxyresin is different from an exact range of the conical surface which isstraight as viewed in cross section. To be precise, the experimentallyobtained range may be greater than the range of the conical surface, andmay include a loosely curved section between the conical surface and thecircumferential lip. In the present invention, a total contact length LCmay be defined as an experimentally obtained value including a range ofthe loosely curved section, and can be determined to satisfy thecondition of equal to or greater than 0.15 mm and equal to or smallerthan 0.8 mm.

EXAMPLES

Examples of the photo film cassette and experiments contacted therewithare described now. FIG. 8, for results of tests on repeated advance ofthe photo film, illustrates a relationship between the number of timesof repeated advance of the photo film and the angle of the inclinedcontact faces 9 a and 9 b of the lip. According to the graph, it isobserved that the number of times of repeated advance of the photo filmwas decreased according to the greatness of the angle of the inclinedcontact faces 9 a and 9 b of the lip. When the repeated advance issuccessful for 500 or more times, there is no problem in practicalperformance of the photo film cassette as a product. It is concludedthat a preferable range of the angle of the inclined contact faces 9 aand 9 b is 50° or less.

TABLE 1 indicates the results of tests on an amount of plastic powderfrom scrape or abrasion of flanges inside a camera FIG. 9 is a graphplotted according to the results in TABLE 1.

TABLE 1 Length L of Angle θ of Powder Samples inclined contact inclinedcontact created Nos. faces 9a and 9b faces 9a and 9b in camera 1 0.1 mm5° X 2 0.1 mm 23° X 3 0.1 mm 50° X 4 0.15 mm 5° B 5 0.15 mm 10° A 6 0.15mm 23° A 7 0.15 mm 35° A 8 0.15 mm 50° B 9 0.2 mm 5° A 10 0.2 mm 10° A11 0.2 mm 23° A 12 0.2 mm 35° A 13 0.2 mm 50° A 14 0.5 mm 5° A 15 0.5 mm10° A 16 0.5 mm 23° A 17 0.5 mm 35° A 18 0.5 mm 50° A 19 0.7 mm 5° B 200.7 mm 10° A 21 0.7 mm 23° A 22 0.7 mm 35° A 23 0.7 mm 50° B 24 0.8 mm5° B 25 0.8 mm 10° A 26 0.8 mm 23° A 27 0.8 mm 35° A 28 0.8 mm 50° B

Condition of the test. 100 test products for each of the samples wereprepared by changing the length L of the inclined contact faces 9 a and9 b. The samples were limited with θ≦50° after the tests of changing thenumber of the times of the repeated advance of the photo film. Thesamples were cleaned sufficiently, and then loaded with new photo film.Tests for taking exposures were conducted in a camera for the 100products of the samples. Then the camera was disassembled to observe adistribution state of the scraped powder or dust inside it. The photofilm used with the photo film cassette was NEXIA H (trade name,manufactured by Fuji Photo Film Co., Ltd.) of 40 exposures. Each camerawas tested with the 100 products of the samples. The amount of thescraped powder was evaluated by human eyes.

Evaluation of occurrence of the scraped powder.

A: No powder was created.

B: Powder was created, but did not cause problems in practical use.

X: Much powder was created and caused problems in practical use.

In observation of those results of the experiments, it was found thatproblems of scraped powder of flanges were prevented from occurrence ifthe various conditions are satisfied within the region A hatched in thegraph of FIG. 9. In the region A, the inclination angle θ of theinclined contact faces 9 a and 9 b is 5-50°, and desirably 10-35°. Thelength L of the inclined contact faces 9 a and 9 b is 0.15-0.8 mm, anddesirably 0.2-0.5 mm.

In FIGS. 10A-10C, other preferred circumferential lips are depicted. InFIG. 10A, a rim portion 58 a of has a peripheral edge 60 being roundedoff. A reference numeral 59 a designates a contact face. In FIG. 10B, arim portion 68 a has an outer ring-shaped face 70 disposed about acontact face 69 a. The outer ring-shaped face 70 is conical, andinclined in a direction opposite to that of the contact face 69 a. InFIG. 10C, a rim portion 78 a has an outer ring-shaped face 80 disposedabout a contact face 79 a. The outer ring-shaped face 80 is flat, andparallel with the reference plane L1.

In the above embodiments, the inclination angle θ of the inclinedcontact faces 9 a and 9 b satisfies 5°≦θ≦50°. However, the inclinationangle θ may satisfy θ>0°, because the inclined contact faces 9 a and 9 bwith the inclination angle θ slightly smaller than 5° may be barelyusable.

In the above embodiments, the length L of the inclined contact faces 9 aand 9 b satisfies 0.15 mm≦L≦0.8 mm. However, the length L may be set alittle greater than 0.8 mm, because the inclined contact faces 9 a and 9b with the length L slightly greater than 0.8 mm may be barely usable.

In FIGS. 11A-13C, still another preferred embodiment is illustrated,including support projections 66 c and 67 c. In FIGS. 11A and 12A,flanges 66 and 67 have a two-stepped cup shape. The flanges 66 and 67have respective holes 66 a and 67 a, into which a spool core isinserted. Circumferential lips 66 b and 67 b wrap ends of the roll ofphoto film, to transmit rotation of the spool core to the outer turns ofthe roll, and also to keep the photo film from being loosened inside aphoto film cassette. The flanges 66 and 67 are respectively molded fromnylon-modified polyphenyl ether resin with which carbon black is mixed,as sufficiently soft plastic material easily deformable in the course ofadvance of the photo film. Each of the flanges 66 and 67 has a weight of0.5 gram or less, and an average thickness of 0.4 mm or less. Preferablythe flanges 66 and 67 have a weight of 0.01 gram or more.

In FIGS. 11B and 12B, the support projections 66 c and 67 c are formedon the flanges 66 and 67 in positions on their bottom. In FIG. 13C, thesupport projections 67 c of the flange 67 are semi-spherical, and has aheight t of 0.02 mm, and a diameter r of 0.15 mm. The supportprojections 66 c of the flange 66 have the same dimension as the supportprojections 67 c of the flange 67. The support projections 66 c and 67 care effective in reducing an area of the contact between the conveyingpath and the bottom surface of the flanges 66 and 67 in the course ofconveyance by use of a part feeder to be described later. The conveyanceof the flanges 66 and 67 is prevented from being influenced by theelectrostatic charge.

The flanges 66 and 67 as a molded product are respectively conveyed andsupplied by a part feeder. The conveyance and supply of the flange 67are the same as those of the flange 66. Only the flange 66 is hereindescribed. A part feeder is constructed to regularize a great number ofthe flanges 66, and transfers them to an assembly line. The part feederis constituted by a bowl feeder and a conveying path connected with anexit of the bowl feeder.

The bowl feeder includes a bowl and a box-shaped support. A great numberof flanges 66 are randomly poured into the bowl. A vibrator mechanism(not shown) is contained in the box-shaped support, and separates theflanges 66 from one another. A rotating mechanism (not shown) rotatesthe flanges 66 in one rotational direction, and causes them to advancethrough the conveying path.

The conveying path consists of a passageway which is shaped like achannel as viewed in the cross section, and causes the flanges 66 to bemoved in an aligned manner one after another. The conveying path extendsfrom the bowl feeder to an assembly line for the photo film cassette.

In the assembly line, each one of the flanges 66 from the conveying pathis picked up by an actuator, and is caused to receive insertion of thespool core moving through the assembly line, to be combined with thespool core.

The conveying operation of the part feeder is described. In the processbefore combining the spool core with the flange 66, the bowl feeder isfilled with a great number of flanges 66. The flanges 66 have beenpackaged in a bag in a randomly collective manner. An operator opens thebag and pours the flanges 66 into the bowl feeder. In the pouringoperation, the flanges 66 are rubbed on one another to cause occurrenceof electrostatic charge. The flanges 66, which are thin and light, areattracted to one another by the charge, and come to overlie on oneanother.

The bowl feeder causes the flanges 66 to rotate and vibrate. The flanges66 are gradually regularized in one direction and aligned. The flanges66 move along a spiral rail inside the bowl, and exit through theconveying path in the aligned state. In FIG. 11B, the supportprojections 66 c are so formed on the flange 66 that the contact areabetween the conveying path and the flange 66 is reduced. Thus failure inthe conveyance is avoided, as no electrostatic charge attracts theflanges 66 to one another, or overlays the flanges 66 in an inseparablemanner.

Note that the number of the support projections 66 c and 67 c ischangeable, and can be determined to represent information of a moldcavity used for forming the flanges 66 and 67. For example, fivedifferent flanges A-E are formed discernibly in the shape. The flange A,as viewed in the bottom plan, has two support projections located in itstop. The flange B has two support projections located in its top and onesupport projection located in its bottom. The flange C has two supportprojections located in its top and one support projection located in itsright. The flange D has two support projections located in its top, onesupport projection located in its bottom, and one support projectionlocated in its right. The flange E has two support projections locatedin its top, one support projection located in its bottom, one supportprojection located in its left, and one support projection located inits right. Even the single mold has plural cavities, each of the flangescan be discriminated as to which cavities the flanges has been producedfrom. This is effective in monitoring the quality of each of thecavities. The quality of the flanges can be checked easily.

It is to be noted that structures different from the semi-sphericalsupport projections may be used for the purpose of reducing the contactarea. A flange can have a ring-shaped ridge of a small width on itsbottom, to form a step on the bottom. Also a flange can have fourarc-shaped ridges respectively between adjacent two of ratchet holes.

EXAMPLES

The effectiveness of the flange in relation to the electric charge isdescribed now. Examples of the flexible flanges are conditioned asfollows:

Material: nylon-modified polyphenylene ether;

Electrification characteristic: volume resistivity of 10¹⁶-10¹⁷ (Ω·m);

Temperature of the air: 20° C.;

Humidity of the air: 35%;

Frequency of the vibration: 50-100 Hz;

Range of displacement in the vibration: 0.1-0.5 mm.

A first example is a flange having an average thickness of 0.2 mm, and astep of 0.02 mm. A bottom area of the flange is 63 mm². An area of thebottom in the contact with the conveying path is 5 mm². The contact areacoefficient S (%) is determined as a ratio of the area Q mm² of thebottom in the contact with the conveying path to the whole bottom area gmm². As the weight of the flange is 46 mg, the contact area coefficientS (%) is {fraction (5/63)}×100 =8(%). Therefore the weight per unit areais 9.2 mg/mm². In the experiment, the plural flanges of this conditionwere poured into the part feeder. The part supply coefficient became150% per unit time when 10 minutes lapsed after the start. The voltageof electrification was 0 kV both before the start and upon the lapse of10 minutes. Note that an electrostatic charge measuring devicemanufactured by Shimuko Co. was used for the measurement of the voltageof electrification.

A second example is a flange having an average thickness of 0.2 mm, andregularly arranged 12 semi-spherical support projections, each of whichhas a height of 0.02 mm, and a diameter of 0.15 mm. A bottom area of theflange is 12.8 mm². An area of the bottom in the contact with theconveying path is extremely as small as 0 mm². Assume that six semispherical support projections among the twelve have been collapsed. Leteach flange have a weight of 40 mg. Then the contact area coefficient S(%) is 55%. Therefore the weight per unit area is 4.2 mg/mm². In theexperiment, the plural flanges of this condition were poured into thepart feeder. The part supply coefficient became 150% per unit time when10 minutes lapsed after the start. The voltage of electrification was 0kV both before the start and upon the lapse of 10 minutes. Note that anelectrostatic charge measuring device manufactured by Shimuko Co. wasused for the measurement of the voltage of electrification.

In conclusion, the flanges according to the present invention made itpossible for the part feeder to supply it without being influenced byelectrostatic charge even with the humidity of 40% or less. The changein the part supply amount due to changes in the humidity was reduced, tostabilize the supply of the flanges.

In FIGS. 14A-16C, another preferred embodiment is illustrated, in whichmoldability of the flange is improved. A flange 128 of FIG. 14B hasholes 128 b to be engaged with ratchet claws. The holes 128 b arearranged in a circular manner. The holes 128 b are an even number, forexample six, in view of engagement with the ratchet claws. It ispreferable that short radial segments defined between the holes 128 bare numerous and thick, for the purpose of facilitating flow of resin inthe course of injection molding with an extremely small thickness. Incontrast the size of the holes 128 b should be great enough to receivethe ratchet claws. However the greatness is inconsistent to thegreatness of the short radial segments, and thus to the ease in moldingof resin. Accordingly the six holes 128 b are the most preferable, asthe holes 128 b have a length equal to or 1.2 times as much as that ofthe ratchet claws in the rotational direction. The changes in rigidityof the flange 128 in the course of one rotation are reduced incomparison with a four-holed flange. Noise in the rotation is reduced,to suppress creation of resin powder.

In FIGS. 14A and 15A-15C, there is a ridge 151 formed with an innersurface of a circumferential lip 127 b of a flange 127. The ridge 151 issemi-circular as viewed in cross section. The ridge 151 has a foot widthM projecting from the inner surface of the circumferential lip 127 b ina range of 0.1-0.3 mm, a projecting height N of 0.005-0.10 mm, and aradius of a cross-section arc in a range of 0.1-0.3 mm. The innersurface of the circumferential lip 127 b of the flange 127 is inclinedinwards in a range of 1°≦θ10≦10° with respect to an axial direction RLof a spool core, or the rotational axis of the shape of the flange 127.The outer surface of the circumferential lip 127 b is parallel to theaxial direction, or inclined outwards in a range of θ11≦5°.

The periphery of the circumferential lip 127 b of the flange 127 has arim portion 108 a which extends to an outside of the flange with aninclination. An inclination angle θ1 of the rim portion 108 a is 5-50°,more preferably 10-35° with reference to a line L1 passing opposite endsof the circumferential lip 127 b. A conical surface 109 a is formed onthe rim portion 108 a to contact the photo film. A length of the conicalsurface 109 a is 0.15-0.8 mm, more preferably 0.2-0.5 mm.

The circumferential lip 127 b of the flange 127 has a thickness T of0.15 mm or more, preferably 0.16 mm or more. The rim portion 108 a has athickness t of 0.13 mm or more, preferably 0.14 mm or more. A projectingheight hi of the circumferential lip 127 b is 1.15-1.35 mm, preferably1.20-1.30 mm. The flange 127 has an average thickness of 0.1-0.3 mm,more preferably 0.15-0.20 mm, and has a diameter r of 18-30 mm.

In FIG. 14B and 16A-16C, there is a ridge 152 formed with an innersurface of a circumferential lip 128 c. The ridge 152 is semi-circularas viewed in cross section. The ridge 152 has a foot width M projectingfrom the inner surface of the circumferential lip 127 b in a range of0.1-0.3 mm, a projecting height N of 0.005-0.10 mm, and a radius of across-section arc in a range of 0.1-0.3 mm. The inner surface of thecircumferential lip 128 c of the flange 128 is inclined in a range of1-10° with respect to an axial direction of the spool core. The outersurface of the circumferential lip 128 c is parallel to the axialdirection, or inclined outwards in a range of 5° or less.

In FIGS. 16A-16C, the periphery of the circumferential lip 128 c of theflange 128 has a rim portion 108 b which extends to an outside of theflange with an inclination. An inclination angle θ2 of the rim portion108 b is 5-50°, more preferably 10-35° with reference to a line L1passing opposite ends of the circumferential lip 128 c. A conicalsurface 109 b is formed on the rim portion 108 b to contact the photofilm. A length L of the conical surface 109 b is 0.15-0.8 mm, morepreferably 0.2-0.5 mm.

The circumferential lip 128 c of the flange 128 has a thickness T of0.15 mm or more, preferably 0.16 mm or more. The rim portion 108 b has athickness t of 0.13 mm or more, preferably 0.14 mm or more. A projectingheight h2 of the circumferential lip 128 c is 1.30-1.50 mm, preferably1.35-1.45 mm. The flange 128 has an average thickness of 0.1-0.3 mm,more preferably 0.15-0.20 mm, and has a diameter r of 18-30 mm.

The flanges 127 and 128 are formed by an injection molding apparatusknown in the art. The injection molding apparatus (not shown) isconstituted by an injection unit and a mold unit. The injection unitkneads resin to be molded for injection. The mold unit is constituted bya mold set and a mold shifter mechanism. The mold set includes a movablemold and a stationary mold. The mold shifter mechanism moves the movablemold up and down.

In the mold set, there are guide pins in its side positions to extend inparallel with one another. The mold shifter mechanism move the movablemold in a direction along the guide pins. It is possible to use a familymold set in which the flanges 127 and 128 of the two kinds can be moldedat the same time. For this family mold set, a three-plate type ispreferable, which is constituted by a stationary mold, an intermediatemold and a movable mold. A sprue, a runner and a gate are disposedbetween the stationary mold and the intermediate mold. A flange ormolded product is obtained between the intermediate mold and the movablemold.

A gate is formed in the center of the stationary mold for pouring meltedresin into the mold set. An end of a runner lock pin appears at acold-slug well of the movable mold. The runner lock pin is a releasemechanism for the molded product. When the movable mold starts beingopened, the runner lock pin pulls the molded flange. When the movablemold opens entirely, the runner lock pin pushes out the flange. Notethat a knockout pin may be used instead of the runner lock pin forknocking the flange. The molded flange has a runner formed with resin inthe gate. The runner is cut away by a punching machine in a position ofa disk gate, to form a hole 127 a. Similarly a runner is cut away fromthe flange 128 to form a hole 128 a. It is to be noted that the runnercutting may be effected inside the mold set immediately after themolding.

The ridges 151 and 152 being formed, the flanges 127 and 128 aresolidified in the course of the molding of the mold unit in a statewhere the ridges 151 and 152 are captured in associated partial cavitiesin the movable mold. After the molding, the mold shifter mechanism movesup the movable mold away from the stationary mold to open the mold set.The flanges 127 and 128 remain on the movable mold while keeping thecaptured state of the ridges 151 and 152 in the partial cavities in themovable mold.

When the mold set opens, the flanges 127 and 128 i nevitably remain onthe movable mold where the runner lock pin is disposed. It is possibleto mold the flanges 127 and 128 consecutively in a stably automatedmanner without much time after releasing the flanges 127 and 128 beforeinjection for the next time. There occurs no problem of remaining theflanges 127 and 128 on the stationary mold which does not have areleasing mechanism.

To ensure the consecutive operation of molding, it is also preferableinstead of the ridge to form a groove in an inner surface of acircumferential lip of a flange. In molding operation, the flange issolidified in a state where the groove is engaged with a partial core ona mold for forming the groove. The flange remains on the movable mold.Thus it is reliably possible to mold flanges consecutively.

The groove in the flange has a preferable depth S of 0.01-0.05 mm, and apreferable width M of 0.1-0.3 mm.

It is also to be noted that the ridge or the groove in the presentinvention may be formed in a continual manner, in which plural shorterridges or grooves are arranged with gaps in a circular manner.Furthermore the ridges or grooves may be formed in two or more lines.

To ensure the consecutive operation of molding, it is also preferableinstead of the ridge to form a rough surface in an inner surface of acircumferential lip of a flange. In molding operation, the flange issolidified in a state where the rough surface is engaged with acorresponding surface on a mold for forming the rough surface. Theflange remains on the movable mold. Thus it is reliably possible to moldflanges consecutively.

Roughness of the rough surface on the flange is in a preferable range of5-30 μm. The rough surface is formed in a preferable width which isequal to or more than 0.1 mm, and equal to or less than a projectingheight of the circumferential lip.

The flanges 127 and 128 are formed by injection molding. The injectionspeed of the injection molding is 300-1,500 mm per second, preferably400-1,000 mm per second. In the injection molding, a range of resintemperature is 260-320°C. A range of mold temperature is 60-120° C.

The flanges 127 and 128 are formed from nylon-modified polyphenyleneether. There are various types of nylon-modified polyphenylene ether aspolymer alloy. Examples of this in the present invention are polymeralloys formed polyphenylene ether and one selected from amongpolycaprolactam (nylon 6), polyhexamethylene adipamide (nylon 66) andpolylaurin lactam (nylon 12).

To the nylon-modified polyphenylene ether, silicone is added in a rangeof 0.5-3.0 wt. %, preferably 0.8-2.3 wt. %. Carbon black is also addedin a range of 0.01-3.0 wt. %. Should the silicone be less than 0.5 wt.%, there is no effect of lubricity. Should the silicone be more than 3.0wt. %, the resin cannot be kneaded sufficiently, as a screw of a kneaderslips with the resin.

EXAMPLES

Examples of flanges for the photo film cassette are described. In thefollowing, a term “Step height” represents a projecting height of thecircumferential lip, “A-flange” represents the first flange, and“B-flange” represents the second flange.

[Example 1] the ridges 151 and 152 formed on the lip inner surface;

arc-shaped as viewed in section;

continuous in a rotational direction;

width M of the ridge foot: 0.1-0.3 mm;

radius R of the ridges: 0.1-0.3 mm;

height N of the ridges: 0.01-0.05 mm;

position of the ridges: a central position of the lip inner surface.

[Example 2] the groove formed in the lip inner surface;

semi-circular or arc-shaped as viewed in section;

allowably triangular or trapezoidal;

continuous or intermittent in the rotational direction.

width of the groove foot: 0.1-0.3 mm;

radius R of an inner shape of the groove: 0.1-0.3 mm;

depth of the groove: 0.01-0.05 mm;

position of the groove: a central position of the lip inner surface.

[Example 3] the rough surface on the lip inner surface;

roughness of the rough surface: 15-25 μm;

width of the rough surface: 0.3-1.2 mm;

preferably continuous in the rotational direction, and allowablycontinual with gaps;

position of the rough surface: position without contact between the lipinner surface and the photo film in the state of winding the photo film.

As a result of experiments, the flange of a parallel shape was obtainedwithout deformation in its top and middle step by the virtue of theridge, the groove or the rough surface.

Evaluation and comparison were made between a photo film cassetteincorporating this flange, and one incorporating a comparative flange,which had been deformed by knocking out and had the “Step height”apparently increased by approximately 5%.

Two kinds of the flanges different in the “Step height” were placed inthe photo film cassette, and evaluated. In the A-flange, the “Stepheight” was 1.25 mm. In the B-flange, the “Step height” was 1.40 mm. Theaverage thickness was 0.17 mm. The thickness of corner portions wasabout 0.15 mm.

Among the comparative deformed flanges, the A-flange had the “Stepheight” of 1.32 mm. The B-flange had the “Step height” of 1.47 mm. Theyhad the thickness equal to that of the novel flange without deformation.

In the evaluation of the performance, the resistance to the advance ofthe photo film was reduced by approximately 20%, from 60 grams to 50grams. Noise in the rewinding operation of the photo film into thecassette shell was reduced from 72 dB to 68 dB, as measured at adistance of 15 cm.

A ridge on the lip inner surface resulted in higher intensity, andhigher force for pinching the photo film. The force for advancing thephoto film was increased. As the outer surface of the photo film wassupported by the ridge, the photo film edges did not contact the lipinner surface. The photo film edges were effectively protected. Therewas little influence to performance of photo film. Performance of thephoto film cassette was raised in total.

Although the present invention has been fully described by way of thepreferred embodiments thereof with reference to the accompanyingdrawings, various changes and modifications will be apparent to thosehaving skill in this field. Therefore, unless otherwise these changesand modifications depart from the scope of the present invention, theyshould be construed as included therein.

What is claimed is:
 1. A photo film cassette comprising: a spool coreabout which a photo film is wound; and a first flange secured to saidspool core; wherein said first flange includes (a) a first lip wrappingaround a lateral edge of an outer-most turn of said photo film, whereinsaid first lip has an inner surface that confronts a major surface ofsaid photo film; and (b) at least one ridge disposed on said innersurface and projecting toward said photo film.
 2. A photo film cassetteas defined in claim 1, wherein said first lip has an outer surface thatfaces away from said photo film; and during molding of said first flangefrom resin, said at least one ridge sets a release of said inner surfacelater than a release of said outer surface.
 3. A photo film cassette asdefined in claim 1, wherein said first flange has an average thicknessof 0.1-3.0 mm, and a diameter of 18-30 mm.
 4. A photo film cassette asdefined in claim 1, comprising: a second flange secured to said spoolcore such that said photo film is interposed between said first and saidsecond flanges; wherein said second flange includes a second lip; saidfirst lip has a projecting length of 1.15-1.35 mm; said second lip has aprojecting length of 1.30-1.50 mm; said inner surface of said first lipand an inner surface of said second lip are inclined at an angle of 1-10degrees to decrease a radius thereof toward an outside edge thereof;respective outer surfaces of said first and said second lips extend oneof substantially erectly, and inclined at an angle of at most 5 degreesto increase a radius thereof toward said outside edge thereof.
 5. Aphoto film cassette as defined in claim 1, wherein said at least oneridge is arc-shaped as viewed in section, and extends in a ring shape ina circular direction of said inner surface.
 6. A photo film cassette asdefined in claim 1, wherein a projecting height of said at least oneridge is 0.005-0.10 mm.
 7. A photo film cassette as defined in claim 1,further comprising: a second flange secured to said spool core such thatsaid photo film is interposed between said first and said secondflanges; wherein said first and said second flanges are formed byinjection molding with resin temperature of 260-320° C., with moldtemperature of 60-120° C., and injection speed of 300-1,500 mm persecond.